How shall you convert a galvanometer into an Ammeter

How should you convert a galvanometer into a voltmeter?

A galvanometer coil has a resistance of 12 Ohm and meter shows full scale deflection for a current of 3 mA . How will you convert the galvanometer into a voltmeter of range O to 18 V ?

A galvanometer of resistance 50 Omega gives full-scale deflection for a current of 0.25 A. Calculate the required resistance to convert the galvanometer into an, ammeter of range 5 A.

How should you convert an ammeter to a voltmeter?